Nilstat is really bad for getting rid of thrush. Thrush is very resistant to it. You will get better results using Daktarin oral gel. On the packet it says not to use it for babies under 6 months. This is because if you put a spoonful of it in the babies mouth like it says to on the packet they may choke because it is sticky. However what you can do for babies under 6 months is instead smear it on your nipples before breastfeeding, and get some on your finger and smear it around their mouths. Ask you child health nurse for advice on how to use it. I think the ABA helpline can also go over how to use it with you on the phone. If you go to a chemist they may not give it to you for a baby under six months without a prescription, because as I said before it may be a choking risk if you use it like it says on the packet. Do
not use it according to packet directions.
Also look at Kellymom for ideas. But do get it treated because it is terrible if it gets entrenched, especially on your nipples. Do go and ask your child health nurse or ABA about using Daktarin oral gel instead of Nilstat. You could also try asking your GP or pharmacist, but unfortunately alot of them don't have as much experience in this area. Anyway, google it, I think the Royal Womens in Melbourne has guidelines online about how to treat little babies under 6 months with Daktarin oral gel.
Good luck OP!!
eta: I found the link for you OP. Here it is:
http://www.thewomens.org.au/ThrushinLactation